This lady crossed the line by a couple miles. What's the difference between this and armed robbery?
Nothing, and that's the point.
Had he left his tools in her apartment and she'd simply closed and locked the door, that would have been one thing, and it might have been very difficult to stick a robbery charge.
However, "the customer allegedly took a bag of the technician’s tools, brought them into her home, and locked the door." That's robbery, and would easy to make that stick. Opening the door while holding a gun, however, doesn't make that armed robbery. In order for it to be armed robbery, she would have had to use the firearm in a conspicuous manner when she took the tools (most states) or merely been armed (some states) while taking them.
And there's the rub: Merely being armed while inadvertently walking out of a store with merchandise you for which you forgot to pay is worse than shoplifting in some locals. It's armed robbery.
Similarly, getting into an argument with someone while armed can, in some locales, bump that up to some pretty serious charges. If you're armed in those places, the law expects you to walk away, regardless of how much you might be in the right with respect to the argument itself. By simple virtue of the fact you're armed, you can be seen in the eyes of the law as wrong.
While some things are fine when you're unarmed, they can get you into major hot water when you're armed. This isn't about the one example mentioned in the OP. It's about any and all such instances.
What are those things?
Come on, folks - this is a discussion forum. Discuss!